Recomendations for imap server

Hi.

I have a home server, with postfix and pop3 through qpopper.
I use thunderbird in my home PC to read mail from several accounts and store it localy.
There are two problems:
one, the mail directory of thunderbird is huge
second, I cant access my old mail from everywhere

So I want to install a imap server, and transfer all my thunderbird saved mail to the imap.

First question has pop-up is which imap server?
I have seen I have several different imap servers in opensuse (15.1)
*imap
*courier-imap
*cyrus-imapd

Which one should be better?
I would prefer the simpler one.
I have found some comparatives between cyrus and courier and dovecot.
Is it the “imap” on opensuse dovecot? the doc only says “This package contains IMAP4, POP2, and POP3 mail servers”

best regards

You can use thunderbird for imap account.
I had a pop3 mail account on thunderbird and moved it to a imap account.
The total size of the mails was 520MB
Basic steps that I used
1 Took a backup of the mails folders (~/.thunderbird/xxxxxx.default/)
2 Moved the inbox, send mail to local folders
3 I Saved the local folders and disabled the pop 3 account
4 Then I created the imap account
5 I tested the imap account
6 I created sub-folders in the imap account This created xxxx.msf and xxxxxx files in the ~/.thunderbird/xxxxxx.default/ImapMail/imap.your_account_name)
7 I leaved thunderbird and copied some saved local folders (xxxx.msf and xxxx files) in the ~/.thunderbird/xxxxxx.default/ImapMail/imap.your_account_name. (accessible from my linux box, my smartphone and a windows laptop)
8 Restart thunderbird and control that the old data are present
9 The other saved folders were copied to a new local folder (only accessible from my linux box)
As far as I remember the *.msf files are rebuild by thunderbird when restarting.

You can aslo import the saved mail via import tools in thunderbird see http://forums.mozillazine.org/viewtopic.php?p=10844567

Regards
Philippe

IMHO you are describing a POP3 vs. IMAP client. The OP wants to run an IMAP server.